The invention relates to a plant for the coal carbonization, or gasification, or both, having at least one burner arranged at the top in a reaction chamber for the partial combustion of finely-ground coal above the ash-melting temperature, and a bottom discharge opening for the gas-coke dust current with following heat exchangers, as well as a separation plant for the gas and the solids.
Such a plant is described in U.S. Pat. No. 3,991,557. In this plant, finely-ground coal is prepared, if necessary, by oxidation with air at low temperature in order to reduce the caking, and blown into a reaction chamber where it is carbonized or gasified, or both, with air, with oxygen-enriched air, or with an oxygen-steam mixture. The resulting gas-coke-dust-slag- or ash mixture is withdrawn from the bottom end of the reaction chamber and fed first to a waste-heat boiler in order to use the heat contained in the gas-solid mixture to generate steam. Subsequently, the gas-solid mixture is fed to a cyclone in which the gas and solids are separated. The coke dust is fed to a storage bin and the gas is fed over a heat-exchanger to a gas-purifying plant to produce a purified product gas required in the reaction chamber.
Though the temperature in the reaction chamber should be above the ash- or slag-melting temperature, that is, above 1,500.degree. C., it is an open question why this should be so. Furthermore, it cannot be seen how the ashes are separated from the coke dust. The steady and continuous outflow of the ashes raises, however, special technical problems, because the operation takes place in a temperature range in which the slag cakes on the walls of the reaction chamber, for example, or of the cooler, thereby reducing the free flow cross section and the heat transfer. The caking of the slag on the refractory lining is enhanced by chemical reactions with the slag components, primarily iron oxides. The refractory lining can thus be rapidly destroyed so that the plant must be shut down prematurely to replace the lining. Replacement of the lining, however, is only possible when the plant has cooled down sufficiently, and results in considerable labor and cost expenditures.
It is not known how the problems in the reaction chamber resulting from caking are to be solved in the known plant. Furthermore, the waste heat boiler is arranged behind the reaction chamber over a line for which considerable heat losses can be expected.